How to choose the best flea & worm treatment for cats


  • There are many different flea and worm treatments available for cats these days, which can make choosing the right one confusing – especially as most cats need more than one product to stay protected.
  • It's important to know which parasites your cat is at risk of, then you can make sure their treatment plan gives them full protection.
  • It’s also important to make sure you choose a product that won’t be too tricky to give e.g. a tablet, liquid, or spot-on.
  • In this guide, we’ll help you decide which parasite treatments are right for your cat and where to buy them.

Checking your cat’s parasite risk

Your cat’s parasite risk depends on their age, lifestyle, location, and the other animals they interact with. The best way to check your cat’s parasite risk is to speak to your vet, or use a reputable online UK parasite risk checker. As a general rule, most cats in the UK should be regularly treated for:

Depending on where you live and your cat's lifestyle, you might also need to treat them for:

  • Ticks (most commonly found in long grass, woodlands, and areas with lots of wildlife).

Leaving the UK?

Before taking your cat abroad, it’s important to look into the parasite risk for the area you’re visiting and protect them as needed. Contact your vet for tailored advice on parasite risks.

Do indoor cats need treatment?

Yes, indoor cats are still at risk of certain parasites such as fleas and worms so it’s important to protect them too.

Prescription vs non-prescription treatments

Where possible, it’s best to stick to parasite treatments that have been prescribed by your vet.  However, we understand that this isn’t always possible. Therefore, it’s important to understand the difference between other treatments available and how to pick the one that’s best for your cat.


Prescription treatments

  • As the name suggests, prescription parasite treatments can only be prescribed by your vet. For this to happen, your vet will need to have physically checked your cat and assessed their individual needs.
  • After the treatment has been prescribed, you can choose to buy it directly from your vet practice, or from a registered online pharmacy (using the prescription they have written for your cat).
  • Prescription parasite treatment is extremely likely to be safe and effective if used in the right way.
  • We advise using prescription parasite treatments wherever possible.

Non-prescription treatments

If you are unable to get a prescription product, it’s important to understand the difference between the two types of non-prescription products available:

1. Treatments that require your pet’s details

  • These types of treatments can be bought from vet practices, online pharmacies, and from locked cabinets in human pharmacies and pet shops.
  • You won’t require a vet prescription, but you will need to provide some details about your cat, such as their name, age, breed, weight and when they last used parasite treatment. The retailer will use these details to check the product you are buying is safe for your cat.
  • How effective these treatments are varies, some work very well, others less so. These treatments may not be suitable for all pets or situations, and may not consider individual health problems.

2. ‘Off-the-shelf’ products

  • This is the type of treatment that can be picked up ‘off-the-shelf’ in supermarkets, corner shops, human pharmacies, pet shops and online pharmacies.
  • There are no restrictions on the sale of this type of product – meaning you do not need to provide any details about your pet to buy one.
  • This type of treatment tends to be less effective and reliable than prescription products, and may not get rid of fleas and worms.
  • They also won’t be tailored to your cat, so could be unsuitable if they have any specific health problems.

Where to buy your cat’s parasite treatment

Your vet practice

  • Buying flea and worm treatments directly from your vet is one of the best options for your cat. They will stock a wide range of reliable products and will be able to give you advice on which ones to use and how often.
  • Vet practices tend to mainly stock prescription treatments - which require your cat to be seen, and non-prescription treatments – that require you to give some details about your cat.
  • As mentioned above, we advise buying prescription parasite products for your cat where possible.

Online pharmacies

  • If buying online, our vets recommend sticking to prescription products (which means you will need to have a prescription from your vet to buy it) or treatments that require you to provide details about your cat.
  • We don’t recommend buying ‘off-the-shelf’ products (that can be bought without providing any of your pet’s details), because these can be much less reliable.
  • It’s also important to make sure that the website you are buying from has been checked by the Veterinary Medicines Directorate (VMD). If they have been, they will display the VMD logo, which guarantees all products have been safely tested.

Pet shops and human pharmacies:

  • As there is no vet on site at pet shops and human pharmacies, they can’t sell prescription products. Instead, they tend to stock a range of non-prescription products that vary in how reliable they are.
  • If you buy from a pet shop or human pharmacy, make sure you stick to the type of products that come from a locked cabinet and require you to give details about your cat.
  • ‘Off-the-shelf’ products can be bought without needing to give any information –we don’t recommend these as they can be less reliable.

Supermarkets and other shops

  • Typically, supermarkets and corner shops only offer 'off-the-shelf' pet products.
  • Our vets don’t recommend buying these as they can be less reliable.

Spot-on, tablet liquid or collars?

When choosing flea and worm treatments for your cat, it’s important to choose a product that will be easy to give. Thankfully, there are several types available:

  • Spot-on pipette – this involves applying a small vial of liquid to the skin, usually on the back of the neck. For advice on how to apply a spot-on check out our video: How To Apply A Spot On Flea Treatment For Your Cat
  • Tablet or chew – tend to work well if your cat loves their food, as some are flavoured or can be hidden in a treat.
  • Liquid or paste – one of the advantages of using a liquid or paste, is that you can put it directly into your cat’s mouth or mix it with food.
  • Collars – with one exception, flea collars tend to be less effective than the other options - if you are thinking of using a flea collar, talk to your vet first.

Preventing side effects

Side effects from parasite treatments are rare and tend to be mild. They can include:

Always speak to your vet if your cat develops side effects - they will advise you what to do, and might recommend a different product for next time. If necessary, your vet will also report your cat’s side effects to the Veterinary Medicines Directorate (VMD).

Before giving your cat any parasite medication, reduce the risk of side effects by checking a few things, such as:

Is the product suitable for your cat’s age?

Some products are only suitable for certain age ranges. For example, not all are suitable for kittens under 8 weeks old.

Is the product suitable for your cat’s weight?

Before giving your cat the treatment, make sure you have the right dose of product for your cat’s weight. Talk to your vet first if unsure.

Has your cat had previous reactions?

Has your cat had any reactions to medication in the past? If so, check the ingredients and make sure that you don’t give them products with those ingredients.

Are there any other animals in the house?

Check what is in the treatment to make sure it’s not toxic to any other animals in the house. If you are unsure, speak to your vet.


Can I use natural flea and worming treatment for my dog or cat?

No scientific evidence supports the use of natural flea treatments such as diatomaceous earth, apple cider vinegar, garlic, or essential oils. Garlic is toxic to both cats and dogs. It’s also worth noting that many essential oils are poisonous to cats. We recommend sticking to vet approved treatments.

Can I use a flea collar?

With a single exception, our vets discourage flea collars due to their limited effectiveness. The exception is a collar containing 'Imidacloprid' and 'Flumethrin,' proven to work for seven to eight months. This collar is available from vet practices, online pharmacies, human pharmacies, and certain pet shops.

How often should I treat my cat for parasites?

This depends on what treatment you are using. If you bought your cat's treatment from your vet, stick to their guidance. Otherwise, follow the instructions given on the treatment packet.

Can you give flea, tick and worming treatments together?

Yes, some flea, tick and worm products are fine to give together, but always check with your vet beforehand. If it’s the first time your cat is using the treatment, your vet may recommend leaving a few days between products. This is so that if any side effects were to happen, you would know which product caused them.

Can I use flea shampoo to treat fleas on my cat?

Unfortunately, flea shampoos often aren’t effective at killing fleas.

Do I have to treat other animals in the same house?

Yes, you will need to treat any other cats, dogs, and rabbits in the house. You will also need to treat your home with a household flea spray and wash any pet bedding at 60°C.

Can fleas live on humans?

No, cat fleas don’t live on humans. They may bite humans but they cannot live permanently on humans.

How do I get rid of fleas in the house?

The best way to get rid of fleas in the house is by thorough vacuuming followed by the use of a household flea spray.

Published: January 2024

Written by vets and vet nurses. This advice is for UK pets only. Illustrations by Samantha Elmhurst.